[CLI][Compiler] Throw error for public entry function where &signer is not first argument

[alnoki]

Move code compiles for public entry functions that have a &signer as an argument other than in the first position, but functions like this are unusable outside the unit testing framework because, for example the TS SDK assumes ABIs have signer listed first, etc.

Throw a compiler error if the &signer argument is not the first agument